Many analysts see benzene litigation as more than looming. The February 8, 2006 Pittsburg Post-Gazette reports that more than 200 individual lawsuits are pending in one area of Pennsylvania alone.

More than a decade ago, the Post explains, gasoline began to leak from underground storage tanks at four service stations in eastern Pennsylvania. In the end, an underground plume of at least 50,000 gallons spread beneath more than 350 homes in the subdivision of Laurel Gardens, sending fumes into the homes via the sewer system and exposing residents to benzene.

So far, the US Environmental Protection Agency has spent about $25 million to clean up the site, and continues to filter groundwater and vapors in the soil to get rid of the traces of gasoline.

The 200 lawsuits in Pennsylvania relate to one single spill site, when according to the Post, in 2005 federal figures showed a backlog of nearly 120,000 sites nationwide, including more than 4,000 in Pennsylvania, which has the 7th highest number of uncleaned tank leaks in the country.

And the damage awards from benzene cases can be high. In a lawsuit in 2005, a Missouri jury ordered BP Amoco to pay $13.3 million in damages after a woman who lived near a refinery died from contact with benzene.

Early this year, Chris Mercer, editor on BeverageDaily.com and DairyReporter.com, broke the story that benzene has been found in soft drinks and that the FDA and soft drink companies knew about the situation for 15 years and failed to warn the public or take action to make sure benzene was removed from the beverages.

The federal safety limit set for tap water is 5 parts per billion (ppb) and in some states, the legal limit is set as low as 1 ppb.

The benzene levels reported in soft drinks were found to be as high as 79 times the legal limit for tap water. Not surprisingly, class action lawsuits are now being filed against the makers of soft drinks in states all across the country.

Benzene was first discovered and isolated from coal tar in the 1800s. Today, benzene is made mostly from petroleum. Because of its wide use, benzene ranks in the top 20 in production volume for chemicals produced in the US, according to the Agency for Toxic Substances (ATS).

The EPA has classified benzene as a Group A carcinogen, meaning it can cause cancer, and the US Department of Health and Human Services says long-term exposure to high levels of benzene in the air can cause leukemia, and that in as little as five years of exposure to benzene people have died from leukemia.

The ATS and the National Institute for Occupational Safety and Health (NIOSH) develop regulations and recommendations for toxic substances. Their recommendations are expressed as “not-to-exceed” levels in air, water, soil, or food, usually based on levels that affect animals and are then adjusted to levels that will protect humans.

Sometimes these “not-to-exceed” levels differ among federal agencies because they use different exposure times, for instance an 8-hour workday verses a 24-hour day, or different animal studies. The maximum allowable amount of benzene in air during an 8-hour workday is 1 part per million.

Various industries use benzene to make other chemicals, such as styrene for Styrofoam and other plastics, cumene for various resins, and cyclohexane for nylon and synthetic fibers, and some types of lubricants, dyes, detergents, drugs, and pesticides.

According to the EPA, benzene is also used as a constituent in motor fuels, as a solvent for fats, waxes, oils, inks, paints, plastics, and rubber, in the extraction of oils from seeds and nuts, and in photogravure printing.

Benzene is found in the air from emissions of burning coal and oil, gasoline service stations, and motor vehicle exhaust. Natural sources of benzene include gas emissions from volcanoes and forest fires.

The EPA identifies the most serious hazardous waste sites in the nation and then places them on a National Priorities List (NPL), as targeted for long-term federal clean-up. As of September 2005, benzene had been found in at least 1,001 of the 1,662 current or former NPL sites, and the possibility exists, the EPA says, that the number of benzene sites may increase in the future as more sites are evaluated.

Industrial processes are the main sources of benzene in the environment and disposal of products containing benzene and gasoline leaks from underground storage tanks release benzene into water and soil.

According to the ATS, benzene can also pass into the air from water and soil surfaces and in turn, benzene in the air can be deposited on the ground by rain or snow.

Exposure in the general population mainly occurs through breathing air and the top sources of exposure are tobacco smoke, automobile service stations, exhaust from motor vehicles, and industrial emissions. Vapors or gases from benzene containing products such as glues, paints, furniture wax, and detergents can also be a source, ATS says.

People may be exposed to higher levels of benzene by living near hazardous waste sites, petroleum refining operations, and petrochemical manufacturing sites.

For most people, the level of exposure through food, beverages, or drinking water is not as high as through air. However, leakage from underground gasoline storage tanks, landfills or hazardous waste sites can result in benzene contamination of well water.

People with contaminated water can be exposed by drinking the water or eating foods prepared with the water. Exposure can also result, the ATS notes, from breathing in benzene while showering, bathing, or cooking with contaminated water.

Individuals employed in benzene related industries are exposed to the highest levels in petroleum refining, and coke and coal chemical manufacturing, rubber tire manufacturing, and storage or transport of benzene and petroleum products containing benzene.

Other workers who may be exposed, the ATS says, include those in the steel industry, printers, shoe makers, laboratory technicians, firefighters, and gas station employees.

When exposed to high levels of benzene in the air, about half of the benzene passes through the lining of the lungs and enters the bloodstream. When exposed to benzene in food or drink, most of it passes through the lining of the gastrointestinal tract and enters the bloodstream. A small amount can enter the body by passing through skin into the bloodstream during skin contact with benzene or benzene-containing products.

Once in the bloodstream, the ATS says, benzene travels throughout the body and can be temporarily stored in the bone marrow and fat and then converted to products, called metabolites, in the liver and bone marrow.

After exposure to benzene, several factors determine whether harmful effects will occur, as well as the type and severity of adverse effects. Those factors include the amount of benzene exposure and length of time of exposure.

In animals, studies have found that long-term exposure to food or water with benzene can damage the blood and immune system and can cause cancer. Animal studies have also shown neurologic, immunologic, and hematologic effects from inhalation of benzene.

Most of the information available on humans is from studies of workers in industries where exposure to benzene in the air is far greater than the levels normally experienced by the general population.

Brief exposure of even 5-10 minutes to very high levels of benzene in the air such as 10,000-20,000 ppm, can result in death, according to the ATS. Lower levels, such as 700-3,000 ppm, can cause dizziness, drowsiness, rapid heart rate, headaches, tremors, confusion, and unconsciousness.

Eating or drinking food products with high levels of benzene, the agency notes, can cause vomiting, irritation of the stomach, dizziness, sleepiness, convulsions, rapid heart rate, coma, and death.

According to the ATS, excessive exposure to benzene can also be harmful to the immune system, increasing the chance for infection and lowering the body’s defense against cancer.

Studies have shown that people who breathe benzene for long periods of time may experience harmful effects in the tissues that form blood cells, especially the bone marrow. These effects can cause a decrease in blood components. A decrease in red blood cells can lead to anemia, and a reduction in other components can cause excessive bleeding.

Exposure has also been associated with a type of leukemia called acute myeloid leukemia, a cancer of the blood system in which there is an abnormal production of hematologic stem cells, granulocytic leukocytes, red blood cells and platelets.

The medical literature is replete with cases of AML in which benzene exposure has been shown to be the cause. There are a number of variants of AML which can be considered to be part of the same disease, including acute myelomonocytic leukemia, promyelocytic leukemia, and erythroleukemia.

In addition, the bone marrow disease, Myelodysplastic Syndrome (MDS), is considered to be in a pre-leukemic stage and studies such as Hayes RB, et al, have found that MDS is caused by benzene exposure at levels of less than 10 ppm. It is suggested in Irons RD, et al, that benzene-induced MDS is a predisposing event in the pathogenesis of benzene induced hematologic diseases.

Recently, studies on the association of benzene and leukemia have also shown an increase in the relative risk of lymphatic system malignancies in benzene workers. A study by NIOSH detailed an increased mortality from lymphoma and lymphocytic leukemia.

A similar increased risk has been reported by other researchers. In Yin SN et al, rubber chemical workers who were exposed to benzene had a 4 to 5 fold higher risk of lymphoid malignancy than workers not exposed.

Several studies have shown that exposure to benzene also causes non-Hodgkin’s lymphoma (NHL). Italian researchers Costantini et al, presented a paper at the April 2005 American Association of Cancer Research, on benzene exposures of 15 years duration, that showed a significant increased risk for NHL.

In 2004, Swedish researchers in Dryver E, et al, reported a study on NHL and benzene occupational exposure that found the risk of NHL increased from exposure to gasoline, oil products, and solvents.

According to the report, Benzene and Diseases of the Blood: Revisited (2006), by Nachman Brautbar, MD, a complete evaluation of a work force in a benzene using plant revealed many individuals with adverse effects ranging from a mild cytopenia to aplastic anemia of sufficient severity to warrant hospitalization, where levels of exposure to benzen were 10-400 ppm.

Aplastic anemia is a relatively rare, potentially fatal disorder, evidenced by a marked decrease in the number of cells in the bone marrow. Its diagnosis is usually made on the basis of a reduction in the formed elements of the blood, including decreased white blood cells, anemia, and thrombocytopenia. A decrease in all three of these blood cells counts is defined as pancytopenia. It is accepted that these are not two separate diseases but rather a part of a spectrum of bone marrow conditions which can result from benzene toxicity.

According to Dr Brautbar, a follow-up study of 125 workers exposed to 400 ppm of benzene found some workers with persistent cytopenias 9 years later, and that one individual had developed acute leukemia and died. Four more people were reported to have persistent decrease in blood counts, and one worker died of aplastic anemia 9 years after the exposure to benzene had ceased.

Dr Brautbar reports another study, where 51 of 217 previously healthy workers were found to have some hematological abnormalities including 6 cases of pancytopenia. These workers were described as having been exposed to 30 to 210 ppm of benzene for as short a time period as 3 months all the way up to 17 years.

In recent years, the association between benzene and smoking-induced hematopoietic malignancies has been confirmed. Korte et al combined epidemiological data on the health effects of smoking with risk assessment techniques for low-dose extrapolation and assessed the proportion of smoking-induced total leukemia and acute myeloid leukemia attributable to benzene and cigarette smoke.

According to this study, benzene is estimated to be responsible for about one-tenth to one-half of smoking induced leukemia mortality and up to three-fifths of smoking related acute myeloid leukemia mortality. The paper, by Korte et al, lends support to the theory that small amounts of benzene exposure leaves the cellular detoxification system more sensitive to the cumulative exposure to benzene.

Exposure may also be harmful to the reproductive organs. Some women workers who breathed high levels of benzene for many months reported irregular menstrual periods and showed a decrease in the size of their ovaries. Several occupational studies suggest that benzene may impair fertility in women exposed to high levels.

Studies on pregnant animals have shown that breathing benzene also has harmful effects on the developing fetus, including low birth weight, delayed bone formation, and bone marrow damage.

In a recent study in the Archives of Environmental Health, the leukemia rate among residents of Laurel Gardens, Pennsylvania was found to be at least 4.5 times higher than would be expected.

Initially, there were 4 cases of leukemia during the study period among the 663 residents, but since then, 3 more cases have been found, according to the Pittsburg Post-Gazette.

The Post reports that the general risk of someone getting that kind of leukemia is 1 in 25,000, so the high number of cases in a group of fewer than 700 residents is significant, especially since the people effected all lived close to the highest concentration of spilled gasoline.

All that said, there may be something to the assertion that the surge in benzene litigation is beginning to look similar to the early days of tobacco and asbestos litigation.